diff --git a/setup.py b/setup.py
index cc56c6889..78b4cd7e8 100644
--- a/setup.py
+++ b/setup.py
@@ -115,6 +115,7 @@
         "argcomplete",
         "pyparsing != 3.0.2",  # breaks --print-dot (pydot) https://github.com/pyparsing/pyparsing/issues/319
         "cwl-utils >= 0.32",
+        "spython >= 0.3.0",
     ],
     extras_require={
         "deps": [